Local residents reportedly hurled plastic water bottles at the troops throughout the early morning deployment.

A recent poll shows 56.6 percent of South Koreans oppose the deployment of the U.S. missile defense system.

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“The American military is completely ignoring us,” said Kim Choong Hwan, the organizer of the local protest against the THAAD deployment. “We will continue to fight with all means.”

The spokesman for the front-runner in South Korea’s upcoming presidential election said the U.S. military’s deployment of the THAAD was “very inappropriate.”

Kim Sung-joo, an honorary professor at Sungkyunkwan University, expressed concern that the move limits the diplomatic options for the next South Korean president.

“Everything happened when no one was prepared,” Kim said. “The deployment of THAAD will leave few diplomatic options for the next president.”

Kim expressed concern the installation will cause China to more aggressively support the North Korean regime.

“The biggest worry is that the THAAD deployment may push China back to North Korea,” Kim said. “I don’t know how much the South Korean government knew about it beforehand, but its voice on North Korea issues has weakened and has been overlooked by the two powerful countries.”

The rising tensions in the Korean peninsula have already led China to retaliate economically against South Korea with boycotts and travel bans.

The Pentagon said the move is necessary in response to North Korea’s “unlawful weapons program.” It plans to complete the THAAD deployment process in cooperation with South Korea’s military as soon as possible.

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“North Korea’s unlawful weapons programs represent a clear, grave threat to U.S. national security,” the Pentagon told the Yonhap News Agency. “North Korea openly states that its ballistic missiles are intended to deliver nuclear weapons to strike cities in the United States, the Republic of Korea and Japan.”

Now that the THAAD is deployed, it will be difficult for the next South Korean president to change course, regardless of what he or she wants, said Lee Jun-han, a professor at Incheon National University.

“It will be difficult for the next president to reverse the decision because the deployment has already begun — unless a majority of people want this, which is very unlikely,” he said. “What’s clear is it is getting more difficult to predict the U.S. government’s next move.”